[Coco] Segment List Full on backup

[Gene Heskett]

On Tuesday 27 January 2015 00:48:27 Allen Huffman did opine
And Gene did reply:
> Er, how is it possible that backup can give a #217 error? I thought it
> was cloning sector by sector, so what would segment lists have to do
> with it?

You are using another fd.seg entry for every it.sas 
sector*bytes_per_sector. An it.sas setting of 8 is only 2k.

There is room for only 48 entries of the 5 byte fd.seg's in the fd.sector 
and it is not extensible.  So a file being copied will fill the fd.sector 
at 2k+48=96 kilobytes.

If the disk is well used, the parts of the file may be widely scattered 
(fragmented) on the disk.

Very simple solution, dmode _all_ your storage media devices, resetting 
sas=10 or more, its a hex value.  I personally have been using sas=20 even 
on a an 80 track floppy for 20+ years.  OS9's disk allocator will, when 
the file is closed, return the unused bits to the allocation map, so the 
minimum files size of 0 bytes that you get when you "touch" a file that 
does not exist, will use one sector or cluster of sectors, so even if 
sas=FF, os9 will return the other FE bits back to the disk as free as the 
file is being closed.

In fact, unless someone has reverted it, you should see in the latest 
(about a year) pulls that the default sas is now 10.  We are these days, 
dealing with bigger and bigger files never imagined in the early 80's.

A setting of FF guarantees that a .dsk, copied to the coco's hard drive 
via rzsz, is in one piece.  I have done this on my second hard drive, then 
located the file, and adjusted the wpc and ofs of that descriptor to point 
at the first byte of that file. 100% equ to mounting it via dw to one of 
the X descriptors of dw.  I did this a few times before I got dw working, 
but have not resorted to those measures to install a new build of nitros9 
in several years now.

An Alternate way of skinning the cat and doesn't harm the cat. ;-)

Cheers, Gene Heskett
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